Fuel system - pump or relay?

Tiny
LOST IN MUD
  • MEMBER
  • FORD F-150
I have a 2004 f150 5.4 4x4 with 53000 miles on it. 5 months ago it died driving down the road {1 day only} Then ran fine until 3 days ago. Started up at low and high speeds. Will die maybe several times then all at once takes off and runs like a champ. It finally gave a p1235 code. Fuel pressure is at 45.3lbs but that was when it was running normal. Could it be a pump relay or inertia relay unless they are the same? Please help. THANKS
Wednesday, May 23rd, 2007 AT 10:37 PM

1 Reply

Tiny
RUDPRO
  • MECHANIC
  • 224 POSTS
I'd check the fuel pressure regulator. It has a fuel line in and fuel line out and a vacuum hose. With the truck running and a fuel pressure gauge on, pull the vacuum line off the regulator. Pressure should increase 8-12lbs. Put the vacuum hose back on, pressure should return to normal. If not, replace the regulator. Also, if gas squirts out of the regulator when you pull the vacuum hose off, the regulator's bad.
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Thursday, May 24th, 2007 AT 2:37 AM

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